MSE: Log a warning if muxed AV media segment has no A or has no V block
To simplify debugging multiple discontinuity detection edge cases related
to the upcoming relaxation of the "media segments must begin with keyframe"
requirement in Chrome, this change introduces chrome://media-internals
debug log messages when either the audio or video track has no coded
frames within a media segment (for a muxed A/V SourceBuffer).
A previously redundant and now complicating call to the end of segment
callback in the WebM stream parser's Flush() is removed, and the comment
for interface StreamParser::Flush() is corrected to not refer to "Seek".
BUG=229412,542375
R=chcunningham@chromium.org
TEST=ChunkDemuxerTests
Review URL: https://codereview.chromium.org/1564983003
Cr-Commit-Position: refs/heads/master@{#370281}
12 files changed
